Estrogen Regulates the Expression of Retinoic Acid Synthesis Enzymes and Binding Proteins in Mouse Skin

This study investigated how estrogen regulates the expression of retinoic acid (RA) synthesis enzymes and binding proteins in the cycling hair follicle of mice. The researchers found that both exogenous and endogenous estrogen influenced the expression of several RA synthesis components, including DHRS9, ALDH1A1, ALDH1A2, ALDH1A3, CRABP2, RARA, and RARB, in a sex-specific manner. The study used male C57BL/6J mice (n=3) and applied various treatments, including 17-β-estradiol (E2) and its antagonist ICI 182-780 (ICI). The results showed that estrogen's regulatory effects were more pronounced with the E2 antagonist than with the CYP19A1 inhibitor letrozole. The findings suggest that estrogen locally produced in the pilosebaceous unit (PSU) can regulate RA synthesis in an autocrine or paracrine fashion, although the effects varied by location within the hair follicle.